How To Fix 16xx And 21 Error During iPhone 3.1 Restore / Downgrade In iTunes

iTunes sometimes displays following 1601, 1602, 16xx or 21 error code while trying to restore or downgrade iPhone or iPod with firmware 3.1. iH8sn0w has just released a utility named iREB (iTunes Restore Error Bypasser), which provides a workaround to fix these errors.

iREB is available for both Windows and MAC OS environments, download link is given at the end. Tool runs on both iPhone & iPhone 3G with Firmware 3.1, and also on iPod touch 1G. Following steps will help you to use this tool:

After starting iTunes, you need to put your iPhone in Recovery Mode; to do so, hold Home and Power button in your iPhone simultaneously and release Power button after a while (10 seconds approx). Keep on holding Home button, till you see following iTunes error message appearing in iTunes stating.

"iTune has detected an iPhone in Recovery Mode. You must restore this iPhone before it can be used with iTunes"

Close iTunes and Start iREB

Now close iTunes and start iREB, following interface will open.

Now select your device and wait till you get a RED or WHITE screen on your device.

Start iTunes and Restore Original Settings on Your iPhone/iPod

Now start iTunes again and select your device (iPhone/iPod) from iTunes DEVICES tab.

To restore original settings on your Apple device, press and hold left "ALT" button on the keyboard ("SHIFT" button for Windows), iTunes will give you option for Upgrade and Restore, click on "Restore" option in the iTunes and then release the "ALT/SHIFT" button. Select .ipsw file and restore it.

That's all! your problem should be resolved now and you won't be seeing these error messages.

Keep in mind that iREB is just a utility/tool to restore original/custom .IPSW file in your Apple device with iTunes, it's not a jailbreak. Hit on below links to read about jailbreak or unlocking iPhone: